The invention concerns a side disc for axial introduction onto a support disc for a support disc bearing of the rotor of an open ended rotor spinning machine for the optical control of a joining carriage, wherein an interruption of a rotational motion of the support disc about a rotational axis is optically recognized by the joining carriage and a working program for the joining carriage is initiated, with at least one reflecting region of the side of the side disc on the support disc facing a light source but otherwise substantially non-reflecting, wherein the reflecting region in the side disc has one or more reflectors worked into the side disc.
A side disc of this type is e.g. known in the art from DE 41 21 387 A1.
Support discs are used in textile machines to control so-called joining carriages which join torn threads to once more bring this spinning location into operation. A pair of parallel adjacent shafts are driven within the spinning device on each axial end of which a so-called support disc (i.e. a total of four support discs) is disposed. One of these four support discs has reflectors on an outwardly directed side facing a light source, e.g. a laser beam. A portion of the light from the light source is reflected by the reflector and is incident on a measuring device e.g. a photocell so that the photocell receives a portion of the light reflected by the reflector in dependence on the rotational frequency of the support disc. The photocurrent in the photocell is modulated with the rotational frequency of the running disc. If one single reflector is mounted on the disc surface, the modulation frequency corresponds exactly to the rotational frequency of the support disc whereas, with a plurality of reflectors on the disc surface, the modulation frequency is a multiple of the rotational frequency corresponding to the number of reflectors. Should the open-ended spinning machine malfunction, e.g. due to a torn thread, the support discs are no longer driven so that the support disc having the reflectors rotates more slowly until it stops. This decrease in the rotational frequency leads to a corresponding decrease in the modulation frequency of the photocurrent which is seen as a malfunction, e.g. a torn thread, by a suitable control electronics. When the support disc is stationary, a constant photocurrent is imparted to the photocell.
A support disc for the support disc bearing of an open-ended spinner rotor is known in the art from DE 43 13 753 A1 with which the occurence of a malfunction is indicated using a magnetic field line signal generator instead of an optical signal generator, e.g. a pin worked into the support disc and made from a ferromagnetic material.
A support disc is known in the art from DE 93 14 801 U1 with which an optical reflector made from light thin foil is adhesively attached to the surface for indication of malfunction. When the surface becomes worn, the reflector can be replaced by glueing a new component thereon.
These conventional support discs have reflector zones configured in such a fashion that a thin ring-shaped plastic disc having reflecting sections is introduced into the side of the disc facing the light source. These reflecting sectors are ring-shaped and consist generally of aluminum with a mirrored surface which is pressed in a interlocking fashion in corresponding ring-shaped segments within the plastic disc. The plastic disc is introduced into the disc surface in a manner which is resistant to twisting in that axially protruding clamping members of the plastic discs are clamped into corresponding receptacles in the disc surface.
Finally known in the art from the above mentioned DE 41 21 387 A1 is a support disc with which optical reflector zones are configured for indication of malfunction by inserting a thin ring-shaped side disc made from plastic and having reflecting sectors into the side of the support disc facing the light source. Since the conventional reflecting side disc can only be acquired in a modular form it is correspondingly expensive. In addition, it is easily broken, since pressure must be exerted to press the side disc into and out of the disc surface of the support disc.
In the environment of an operating rotor spinning machine, the air is filled with soiling particles such as oil, petroleum benzine, dust and in particular so-called "fly" (fine and extremely fine fiber fragments). Over a period of time, this soilage deposits on and around the side disc. Since the side discs in accordance with DE 41 21 387 A1 are not introduced onto the support disc in a dust-tight fashion, the soilage slowly gains entrance between the side disc and the reflector zone which, over a period of time, strongly reduces the reflectivity. Since the conventional reflecting side discs are built in a modular fashion, removal of the deposited soilage is not possible so that a new reflecting side disc must be introduced into the running disc. If, however, the reflector changes, the production process is substantially encroached upon at this location. In addition, the reflecting plastic disc is normally firmly connected to the support disc (e.g. by glueing) to prevent twisting with respect thereto so that the entire support disc must be exchanged if soilage occurs.
Known in the art from DE 196 02 377 A1 is a support disc having reflectors for open-ended rotor spinning machines with which, in contrast to the side disc in accordance with the invention, circular reflector elements are directly inserted in corresponding depressions on the support disc. Towards this end, among other things, a reflector element is provided for which likewise has a cats-eye structure directly formed on its side facing away from the light source. A covering member is, however, in contrast to the side disc in accordance with the invention, not provided for so that the above mentioned soilage problem is not permanently solved. This is also the case in the other prior art.
It is therefore the purpose of the present invention to further improve a side disc of the above mentioned kind such that the above-mentioned disadvantages of conventional side discs having reflectors, in particular the necessary exchange of the side discs or the support discs due to loss of reflectivity, is avoided.